


The Theft of the Black Diamond

by ShootiNgSt4r



Category: Magic Kaito, 名探偵コナン | Detective Conan | Case Closed, 방탄소년단 | Bangtan Boys | BTS
Genre: Detective Jeon Jungkook, Hoseok is Sonoko, Jimin is Aoko of course, Jimin is Taemin's son, Jin is the handsome but useless detective Kogoro, Jung Hoseok | J-Hope & Min Yoongi | Suga are Best Friends, Jungkook is Shinichi Kudo/Edogawa Conan, Kaitou Kid Heist (Meitantei Conan/Magic Kaito), Namjoon is the genius inventor Professor Agasa, Seo Joon is Jirokichi, Taehyung is V aka Kaito Kid, Yoongi is Ran
Language: English
Status: In-Progress
Published: 2020-04-12
Updated: 2021-02-04
Packaged: 2021-02-28 19:47:19
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 3
Words: 4,287
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23132662
Author URL: https://archiveofourown.org/users/ShootiNgSt4r/pseuds/ShootiNgSt4r
Summary: University student Jeon Jungkook, a famous detective that calls himself the Sherlock of the century, was forced to take a strange drug and was shrunk into a middle school child! Armed with the gadgets that the genius inventor, Kim Namjoon, made for him, he now lives with his former best friend Min Yoongi, and Yoongi's handsome but useless detective cousin Kim Seokjin.One day, a letter from the famous jewel thief, V, arrives for rich bachelor Park Seojoon - in it, V declares that he will take the beautiful engagement ring set with a large black diamond that Seojoon has recently collected! Will V manage to steal the precious jewel, or will Jungkook manage to stop him?
Relationships: Jeon Jungkook/Min Yoongi | Suga, Kim Taehyung | V/Park Jimin
Comments: 4
Kudos: 5





	1. Characters

**Jeon Jungkook = Shinichi Kudo / Edogawa Conan**

Popular university student and detective, Jungkook was famous for easily solving cases that flummoxed the police.

Known for his handsome, chiseled face, sharp jawline, and well muscled body, Jungkook had many fans and appeared on the paper several times.

One day, while at an amusement park with his childhood best friend Min Yoongi, Jungkook witnessed a man in black in the midst of a suspicious transaction. Caught up in watching the deal, he failed to notice the man's partner sneaking up behind him and was forced to take a drug that ended up shrinking him back into a middle schooler.

Now back in the awkward, gangly teenage body that he'd thought he'd left behind forever, Jungkook lives with Yoongi and his detective cousin, Seokjin. Due to his reverting back to how he was before his growth spurt, most people don't recognize him as the formerly popular detective. Still, his mind is as sharp as ever and with the help of the gadgets that his friend and neighbor, Kim Namjoon, made for him, he still goes around solving crimes and revealing the truth.

**Min Yoongi = Mouri Ran**

Jungkook's childhood best friend (and crush), Yoongi is a 3rd year university student majoring in music production. He found out that Jungkook had been shrunk back into a teenager, and took him in to protect and care for him. He has conflicting feelings about the fact that his former best friend (and crush) is now, once again, an underage teenager.

**Kim Seokjin = Mouri Kogoro**

Yoongi's cousin and roommate, Seokjin is a private detective that left the police force a couple of years back. Although popular for his handsome face and charming manners, he is a lousy detective and it's only with the help of Jungkook that he becomes known as a great detective. 

**Kim Namjoon = Professor Agasa**

A genius inventor that lived next door to Jungkook before he was shrunk, Namjoon is a freelance writer that invents things in his spare time. Clumsy, absentminded and a little odd, Namjoon was the first to discover the younger Jungkook, who had passed out in front of his apartment. He supplies Jungkook with ingenious gadgets such as a voice changing choker necklace and a solar powered skateboard.

**Jung Hoseok = Suzuki Sonoko**

Yoongi's best friend since high school and the heir of Jung Corporations, Hoseok is a ray of sunshine that loves to dance and has a huge crush on V, the mysterious jewel thief that the press have taken to calling the Korean Arsene Lupin.

**Kim Taehyung/V = Kuroba Kaito/Kaito Kid**

A handsome photography major during the day and a gentleman thief during the night, Kim Taehyung leads an exciting double life. He is a magician, always entertaining his friends with his magic tricks, and as V, the mysterious jewel thief, he goes around stealing precious gems and evading the police in mysterious, ingenious ways.

**Park Jimin = Nakamori Aoko**

Taehyung's childhood best friend and neighbor, Jimin is a dance major at the same university as Taehyung. He's bright, happy and kindhearted, always helping people and making friends everywhere. He doesn't know that Taehyung is the mysterious V and often complains about V always making his adoptive dad, Inspector Lee Taemin, look like a fool.

**Park Seojoon = Jirokichi Suzuki**

A rich bachelor and Hoseok's uncle, Park Seojoon is famous for collecting rare and precious artifacts from all around the world. He displays them all in his private museum, and considers V a rival to beat. His competitive nature makes him burn with a passion to finally win against the famous thief and send him to prison.

**Lee Taemin = Inspector Nakamori**

Jimin's adoptive dad, Lee Taemin is one of the youngest inspectors in the Seoul police prefecture. He has made V his personal project case, and is therefore present every time V issues a challenge. His dream is to finally capture V, but is bested every single time he goes up against him. 


	2. The Challenge

**Notes for the Chapter:**

> Real black diamonds are actually much more affordable than normal diamonds, but for the sake of the story, we'll pretend that black diamonds are much rarer and therefore much more precious than normal diamonds.

"...and the famous rich bachelor, Park Seojoon, has announced this morning that the newest addition to his collection, the Black Lover, an extremely valuable engagement ring set with a 27 carat black diamond, will be displayed in his museum starting this Friday. The eyes of the public are set on Mr. Park, due to the appearance of a challenge note sent by phantom thief V announcing that he intends to steal the ring this Saturday, at 8 pm sharp. Mr. Park remains confident that he will be able to win this fight against the mysterious jewel thief, and has announced that he has installed a state-of-the-art security system in preparation for the heist. The police have refrained from giving any comment ...."

Jungkook snorted and tossed the remote control away, throwing himself back against the couch cushions. "Typical of the old man," he scoffed, glancing at the large image of Park Seojoon that filled a quarter of the TV screen. "Does he really think he'll win this time?"

Yoongi looked up from where he was reading a book, curled up in the loveseat next to the window. “Well, he’s pretty confident every time, so...”

”How stupid,” Jungkook rolled his eyes, slouching further down.

”Language, young man!” Seokjin yelled as he walked into the room, wagging his finger disapprovingly at him. Jungkook rolled his eyes. Since Seokjin didn’t know about Jungkook’s shrinking, he treated him as a middle schooler all the time, which was pretty annoying. Jungkook couldn’t help but act snarky in front of the older detective, who, in his opinion, was so useless he should have never left the police force and started a detective agency. 

“Are there any hot chicks or cute boys that came in asking for my services while I was gone?” Seokjin asked pompously, perching himself on the office desk and striking an obnoxious pose. Yoongi rolled his eyes. “None,” he told him, used to his roommate’s antics.

”As if they would come to such a useless detective,” smirked Jungkook, dodging when Seokjin threw a Mario figurine at his head.

”You little—“ Seokjin began, seething with fury, when the door was flung open, interrupting his lunge towards the teen.

”Hey everyone, guess what!” an orange haired boy with a huge smile and a loud voice burst in, waving a piece of paper around excitedly. “Oh, hey, Jin hyung,” he added, noticing the comical half lunge Seokjin had frozen in. “You alright?”

Seokjin straightened up and cleared his throat, tugging his suit lapels as he rolled his neck. “Yes, perfectly fine,” he sniffed, giving a death glare to Jungkook, who merely smirked.

”What is it, Hobi?” Yoongi asked interestedly, getting up from the loveseat. 

“It’s the phantom thief, V!” Hoseok, Yoongi’s best friend, yelled excitedly.

”Oh yeah, we just heard about it on TV,” Jungkook remarked, reaching up to pluck the piece of paper out of Hoseok’s hand. “What is this?”

”It’s V’s challenge note, of course!” Hoseok grinned. “God, I’m so excited. Maybe this time I’ll finally get to meet him! Ugh, he’s so hot, I bet he’s super nice too.”

Yoongi and Jungkook exchanged fond and exasperated glances. Hoseok had had a huge celebrity crush on the famous thief V since he’d first appeared on the news, and everytime V sent a challenge note to Hoseok’s uncle, Park Seojoon, he always made it a point to be there no matter what, often dragging Yoongi - and by extension Seokjin and Jungkook - along with him, too.

Hoseok was the heir of Jung Corporations, one of the biggest companies in the whole of South Korea, which meant that he was rich. As in filthy rich, born with a gold spoon in his mouth, etc. But he was extremely good natured and didn’t flaunt his wealth - in fact, most people didn’t know he was a billionaire at all. He and Yoongi had met in high school and had become best friends pretty fast, which had made Jungkook pretty jealous at first. But then he’d noticed that they were a completely platonic couple, so he’d accepted Hoseok’s presence. Hoseok was also unaware of the fact that the moody emo middle schooler Jungkook who lived with Jin and Yoongi was in fact the same person as the famous detective Jungkook, only having met him after his huge growth spurt. He therefore thought of Jungkook as an adorable kiddo who had a cute crush on Yoongi.

Jungkook peered curiously at the letter from V, noticing immediately the signature doodle that the thief signed all his calling cards with. He had a personal rivalry with the sneakthief, since V was the only one who had managed to elude him not only once, but several times. He was also rather curious about what sort of a person V actually was - he seemed young, only around their (as in pre-de-aged Jungkook’s) age, and he always returned the jewels he stole, which left Jungkook curious as to what his motive was for becoming a thief in the first place. He also respected the fact that while he’d fooled the police multiple times, V never hurt or killed anyone, at least not on purpose (except for the multiple bruises and broken limbs certain overeager policemen got by all of them trying to pounce on him at once).

”Uncle Seojoon wants you all to come,” Hoseok continued. “Especially you Jungkook, and Jin hyung, you too.”

”Of course he wants me,” Seokjin scoffed, tossing his hair dramatically. “I’m the famous detective Kim Seokjin, after all!”

Jungkook rolled his eyes. _He_ was the one who had turned Seokjin, who had previously been known as a pretty boy useless detective who couldn’t solve a case to save his life, into a successful detective that solved every case he went on, by shooting him with an anesthetic needle to put him to sleep and using his bow-tie voice-changer to mimic his hyung, solving the crime in Seokjin’s voice. He did this to avoid getting noticed by the press, which would be fatal for him - if the men who had tried to kill him found out that he was still alive, everyone around him would be in danger.

Yoongi and Seokjin were both unaware of this, Yoongi preferring to turn a blind eye to whatever Jungkook was doing and Seokjin actually believing that he had solved all those cases and that he just couldn’t remember them due to the adrenaline rush and all that.

Jungkook wondered how long he could keep up the act without getting caught.

But so far, thanks to his former neighbor and friend Namjoon’s genius inventions, he’d managed to make it this long without getting noticed by the Black Organization.

He remembered the fatal night when he’d run into that very Organization for the first time. He and Yoongi had been on a date - well, they hadn’t officially called it a date, really, but they were alone, just the two of them, and had gone to an amusement park together. How much more ‘date-like’ could you get? reasoned Jungkook. Anyways, it had been a fun and memorable date, and they’d just been about to go home when he’d noticed a couple of really shifty looking men. Unable to ignore them, he’d told Yoongi to go home without him and followed the two suspicious men, finally managing to overhear a suspicious transaction taking place. Too focused on their conversation, he’d failed to notice the other man sneaking up behind him, and had been knocked unconscious. They’d been planning to kill them, but decided it was too risky, with so many people around, and had instead fed him a poison that was still in development and that hadn’t yet been tested on people, leaving him there to die.

When he’d come to, he’d found that his clothes all hung loosely on him now, and that he now seemed quite a bit shorter and definitely a lot less buff than before. It was only when he’d managed to run all the way to his house, only to run into Namjoon in front of the front gate, that he’d realized what had happened. Instead of killing him, the pill had de-aged him, returning him to the body of a 12 year old boy!

Namjoon had been shocked to stumble into the younger version of his friend. He’d recognized him at once, of course, being one of the few friends who’d known him before his growth spurt. He’d taken a shocked and shivering Jungkook back into his house and given him a cup of hot chocolate, asking him what happened. It was him who figured out what had happened, and who convinced Jungkook that he had to stay hidden in order to stay safe. In spite of Jungkook’s pleas, he’d insisted on telling Yoongi, who was Namjoon’s friend, too. Yoongi had been shocked, to say the least, to find Jungkook like that, but had immediately agreed to take Jungkook in, saying that his detective roommate, Seokjin, might be able to help figure out who those suspicious men in black were.

This had been a few months ago already, and Jungkook was, as much as he tried to deny it, now rather used to being a middle schooler again. It was annoying, sure, not being able to show off his deduction skills in front of everyone like before, but he valued his friends’ safety too much to put them in danger like that. So, with the help of some of Namjoon’s ingenious inventions, he’d turned Seokjin into a sensational skilled detective instead, to the older man’s utter (and bemused) delight.

“Come on, guys,” Hoseok called, jerking Jungkook back into the present, “Let’s go!”

They all filed out of the detective agency’s office, hailing a taxi to get to Park Seojoon’s huge estate.

Hoseok chattered non-stop along the way about the phantom thief V and his fantasies about finally meeting V (and making him fall in love with him), which Jungkook basically tuned out, his excited voice turning in to background noise as he mused over the Black Organization, the few leads he had and what he would do once he turned back into himself (confess to Yoongi, of course, and maybe get to finally kiss him and ... *blush*).

He stared out the window of the car, lost in his thoughts, as the sky above them slowly grew darker as night fell. Meanwhile, in another part of the city, another young man was preparing for the night, pulling on a crisp white suit and cloak, tugging a white top hat down over his eyes as he grinned in anticipation for the night ahead.


	3. The Phantom Thief

“Tae? Taaeeeee~ Where are youuu~” a young man with soft blond hair wandered through the empty house, calling for his best friend. “That’s weird,” he frowned when he couldn’t find him anywhere. “He never said he’d be going out.” The man shrugged and left the house, muttering complaints under his breath. “And I made his favorite dumpling soup today, too. That idiot, where’s he gone?”

He crossed the small yard that connected their two houses and entered his own, toeing off his shoes in the entryway.

”Hey, Jimin, where’s Taehyung?” a middle aged man in a police suit asked from the dining table when he entered the room alone.

”Dunno,” Jimin shrugged. “His house was empty. Maybe he had somewhere to go to.”

”Hmm,” the man murmured, frowning.

”Oh well, all the more for us!” Jimin said brightly, ladling the soup into two multicolored bowls. “Here, dad.”

”Thanks,” Taemin hummed, smiling fondly at his son as they sat down to eat together.

They were just about to start eating when the door suddenly burst open, startling them both.

”Hey!” the handsome young man with curly black hair exclaimed, sticking his hands in his pockets as he strolled over to the table, “don’t start the meal without me! Where are your manners?” He stuck out his tongue cheekily at Jimin, who glared at him, folding his arms over his chest.

”You were the one that disappeared without saying anything,” he huffed as Taehyung dropped gracefully into a chair. “Where were you, anyway?”

”Ah, had some things to take care of,” Taehyung shrugged. “Anyways, where’s my food?”

”You can go get it yourself,” Jimin said, turning his nose up at him and scooping up some of his own soup. Before he could eat it, though, Taehyung swooped in and stole the bite, grinning at his best friend who stared at him, flabbergasted.

”Oi, brat, don’t steal my son’s food,” Taemin grumbled, rolling his eyes. Taehyung simply shot him a wink, grinning as he got to his feet and strolled over to the soup pot.

“Oh, yeah,” Jimin continued while Taehyung was still by the stove. “I heard that V’s next heist will take place tonight! Are you ready for him, dad?”

Taemin scowled at the mention of the famous jewel thief’s name. “Of course I am!” he roared, pounding a fist down on the table. “That blasted thief, always making fun of me and the police, disguising himself as us! I can’t forgive him!”

”Whoa, whoa,” Taehyung chuckled as he came back to the table holding a bowl of soup. “Easy there, old man.”

”Who’re you calling old?” Taemin grumbled under his breath, sinking back into his seat.

”Besides, he always returns the jewels he steals, right?” Taehyung continued. “So why all the fuss?”

”It’s the principle of the thing that matters!” Taemin argued. “Besides, why steal things at all if you’re just going to return them right away? He’s making fun of the police, he is! He enjoys making us look like fools in front of the public.”

Taehyung couldn’t help but chuckle to himself. That bit was half true, he admitted. It was fun outsmarting the police, though he wouldn’t go so far as to say he enjoyed ridiculing them on purpose. He had a lot of respect for the police. It wasn’t his fault that he was such a genius when it came to creative getaways and convincing disguises.

Jimin frowned. "I don't like this V guy," he said petulantly. "I think he's just childish and stupid. I don't get all the fuss about how cool he is."

Taehyung winced. One reason why he could never tell Jimin about his alter ego was that Jimin hated the thief for always making a fool out of his dad. Which was another issue - Taehyung was pretty confident that he could evade the police, that wasn't a problem, but he was a little worried that Jimin or Taemin might find out his identity by accident. Either Jimin might run into his secret lair by mistake, or Taemin might catch a glimpse his face and figure out that "wow, he kinda looks really similar to my neighbors' son, aka my son's best friend and the boy I've known for over ten years, I wonder why?". And as much as Taemin liked him, Tae really didn't think that would extend to him protecting his secret and letting him walk free instead of arresting him on the spot.

"Well, I've gotta go now," Taemin sighed, dabbing at his mouth with a paper napkin and rising up from the table. "Gonna go get ready to catch that pesky little sneakthief!"

"Good luck, dad!" Jimin chirped, smiling warmly at his dad who chuckled and kissed the top of his head before picking up his policeman's cap and heading towards the door.

"Good luck catching V!" Taehyung called, grinning widely. Taemin waved a hand in acknowledgement and left, the door slamming closed behind him.

"So! You up for a round of anime?" Jimin asked Taehyung, who gave a guilty smile.

"Sorry, Chim," he said, clasping both hands in front of him in an apologetic gesture. "I promised a friend I'd go over to his house, so I can't today."

Jimin pouted. "But I have nothing to do!" he whined, and Taehyung grimaced. He really couldn't resist Jimin's pouty face, which is why he immediately closed his eyes and raised his head towards the ceiling.

"Nope, nope!" he chanted, shaking his head. "You're not going to use those puppy eyes on me, no no no."

"But Taeee!" Jimin whined, grinning as he tried to force Taehyung to open his eyes, clinging to his front.

"Noooo~" Taehyung groaned, running away as best as he could with his eyes only half open, and Jimin gave chase, giggling madly as he tried to get Taehyung to look at him properly.

They ended up in a heap on the carpeted floor, both giggling hysterically as they wrestled with each other.

"Ha! I win!" Taehyung yelled triumphantly, pinning Jimin down and grinning down at him. Jimin immediately pouted up at him, making Taehyung yelp and slap a hand over his eyes, chanting "nope, nope, nope!" over and over again. Smirking, Jimin took the chance to flip them over, pinning Taehyung down instead and trying to pry his hands off his eyes, growling when his tiny hands couldn't get Taehyung's big fingers fully off his face.

In the end, he gave up, flopping down next to his best friend. "Fine, you meanie," he huffed. "I'll just go watch dad catch V, then."

Taehyung froze. It was never good when Jimin joined Taemin at the scene of the crime, because then Taehyung got distracted trying to never be directly in Jimin's line of sight, afraid that Jimin might somehow manage to recognize him despite his cloak, suit and monocle.

"Ah, but isn't that boring?" he tried. "You should stay at home and start on that new anime series you were talking about the other day instead." 

"But I want to watch it with you!" Jimin complained. "No, I'm gonna go see that stupid V try _and fail_ to steal that ring."

Taehyung winced. Jimin was extremely stubborn and once he'd made up his mind about something, there was no changing his mind.

"Fine, then," he huffed, sitting up. "I'm gonna go get ready, then. Have fun with your dad!"

"Have fun with your _friend_ ," Jimin scoffed, folding his arms over his chest and looking away with a pout. Taehyung grinned, leaning down to kiss Jimin's forehead, making him blush adorably.

"See ya," he chuckled, dodging the cushion Jimin launched at him as he made his way out of the house.

Once he was back in his own room, he carefully drew the curtains over the window that looked out at the yard and had a good view of Jimin's room, just opposite. When they were younger, they'd communicated with each other by secret codes, using flashlights to send short messages to each other at night. Once he'd even tried to crawl over to Jimin's house using a ladder that they balanced on the windowsills of each house. He'd almost died that night, Jimin's piercing scream bringing both their parents running only to find Taehyung clinging desperately to the rungs of the ladder while Jimin sobbed in terror. They'd been scolded terribly, but it hadn't stopped them from doing all sorts of stupid things after that. But it wouldn't do to have Jimin walk into his room and witness what he was about to do now, so he made sure the curtains were properly closed before walking up to the large painting that hung on his wall. Taking a deep breath, he pressed his palm to a certain spot on the painting, activating the mechanism that started whirring, rotating the picture frame and whisking him into the space behind the wall.

The lights flickered on all along the wall, automatically lighting up the dark secret room. A set of stairs led down into a richly carpeted floor, where a single armchair sat facing the back wall. Taehyung plopped down into the armchair as a machine started whirring, selecting a recording from the extensive compilation his father had left for him.

"My dear son," his dead father's voice floated out of the antique gramophone, a faint whirring noise in the background as the recording was played. "in order to be a magician, there is something you must never forget, and that is a child's heart. By the time you'll realize this, you'll be an adult. But even when you're fully grown, never forget that within your adult body, you can still own the heart of an innocent child."

"Yes, dad," Taehyung murmured, a sense of sadness overcoming him as he realized that his father had never seen him as an actual adult. He'd passed away when Taehyung was still in middle school, an unfortunate accident that might not have been an accident at all. He was the reason that Taehyung had taken up his father's mantle, reviving the figure of the phantom thief V who had disappeared without a trace 7 years ago. In order to figure out the secret behind his father's untimely death, he was on a mission to find the precious jewel that the mysterious organization that had killed his father was after. Perhaps, once he found that stone, he might finally be able to understand the reason behind the death of the greatest magician of the 20th century.

As the recording whirred to a stop, a contraption in the middle of the room rose up from the ground, revealing a wooden closet that sprung open to reveal his father, and now his own, signature white suit and cloak, accompanied by a pristine white top hat, white gloves, special monocle, and customized card gun.

Taehyung smirked at his reflection as he donned the outfit, turning into the mysterious jewel thief V. Pulling his top hat down over his eyes, he shot finger guns at himself before turning away. "Let the game begin," he murmured as he left the room, leaving a solemn silence behind.


End file.
